Extended life disposable pulse oximetry sensor

ABSTRACT

An oximetry sensor comprising a foam wrap member including a fastener, back film mounting member, LED assembly and photodiode connected to a cable, support rings for the LED assembly and photodiode, window film for the LED assembly and photodiode, and a top liner.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 08/592,919,filed Jan. 29, 1996, now U.S. Pat. No. 5,891,026.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to sensors applied to the body formonitoring or making measurements of body tissue conditions, metabolismor other body functions indicative of health. More specifically, thepresent invention is directed to a pulse oximetry sensor which can bereadily attached and reattached to a portion of the body in anon-invasive manner.

2. State of the Art

In the prior art, a non-invasive pulse oximetry sensor may be used tomeasure the relative oxygen saturation of the blood. Typically, in suchprior art types of oximetry sensors a light source, such as a lightemitting diode (LED) is used to alternately direct light of twodifferent wave lengths, such as red and infra-red light, to the bloodthrough the skin. The light transmitted or reflected by the blood at thedifferent wave lengths can be then compared to provide a measurement ofoxygen saturation of the blood.

A typical prior art probe system contains the light emitting sources,such as the LED's, and a light sensor, such as a photo diode, mounted onthe appendage of the body, such as a finger, toe, ear lobe, nose, hand,tongue or foot. However, such devices need to be capable of beingreadily attached to the body appendages, comfortable when attached to apatient, reusable on the same patient, and relatively inexpensive tomanufacture.

One type of prior art type oximetry sensor uses the mechanical clampingaction of spring biased jaws to retain the sensor on an appendage of apatient. Such a device is illustrated in U.S. Pat. Nos. 4,685,464 and5,438,986. While such devices are effective, they are inherentlydifficult to clean and inappropriate for the long term use orapplication on a patient.

Another type of oximetry sensor relies upon a deformable member beinglocated in the device to retain the sensor on the appendage of apatient. Such a device is illustrated in U.S. Pat. Nos. 4,865,038,4,928,691, and 5,217,012. During the reuse of such sensors on a patientsince the retaining member has been deformed and has a memory,reinstallation of the sensor may affect the comfort of the patient.Also, such sensors are also relatively expensive to manufacture as thesensors contain a number of components.

In yet another type of oximetry sensor in an effort to facilitate reuseof the sensor and to provide comfort to the patient during use of thesensor, the sensor is retained on the finger of a patient through theuse of hook and loop fabric. However, such sensors have used complexshapes of hook and loop fabric as retaining devices thereby causing themanufacturing expense of the device to increase. Such sensors areillustrated in U.S. Pat. Nos. 4,825,879, 5,209,230, and 5,469,845.

In another type of oximetry sensor, adhesive is used to attach thesensor to a patient in an attempt to lower manufacturing cost of thesensor, provide comfort to the patient during use of the sensor, andprovide a secure attachment of the sensor to the patient. However, sincethe device must be frequently repositioned on a patient, the adhesiveloses its adhesive quality during reuse. Also, the adhesive may irritatethe patient during use thereby causing discomfort. Such sensors areillustrated in U.S. Pat. Nos. 4,830,014 and 5,170,786.

In yet another type of oximetry sensor, an elastomeric member is used toretain the sensor on the finger of a patient. Although this allows reuseof the sensor, the degree of pressure applied by the elastomeric memberand the elastomeric member being in contact with the skin may causediscomfort to a patient. Such a sensor is illustrated in U.S. Pat. No.5,337,744.

Since the prior art sensors are generally either reusable and expensiveto manufacture, or are not easily reusable and have a relatively lowmanufacturing cost, or reusable and cause discomfort to the patient,there is a need for a comfortable, extended life, disposable, lowmanufacturing cost pulse oximetry sensor.

SUMMARY OF THE INVENTION

The present invention is directed to a comfortable, extended life,disposable, low manufacturing cost pulse oximetry sensor. The presentinvention is also directed to the method of making such an oximetrysensor. The oximetry sensor of the present invention comprises a foamwrap member including a fastener, back film mounting member, LEDassembly and photodiode connected to a cable, support rings for the LEDassembly and photodiode, window film for the LED assembly andphotodiode, and a top liner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of the oximetry sensor of the presentinvention.

FIG. 2 is a view of the oximetry sensor of the present invention inrelation to the finger of a patient before the oximetry sensor isinstalled thereon.

FIG. 3 is a view of the oximetry sensor of the present inventioninstalled on the finger of a patient.

FIG. 4 is a view of the first step of the method of manufacture of theoximetry sensor of the present invention.

FIG. 5 is a view of the second step of the method of manufacture of theoximetry sensor of the present invention.

FIG. 6 is a view of the third step of the method of manufacture of theoximetry sensor of the present invention.

FIG. 7 is a view of the fourth step of the method of manufacture of theoximetry sensor of the present invention.

FIG. 8 is a view of the oximetry sensor of the present invention.

The oximetry sensor and the method of manufacture of the presentinvention will be better understood when the drawings are taken inconjunction with the description of the invention.

DESCRIPTION OF THE INVENTION

Referring to drawing FIG. 1, the oximetry sensor 10 of the presentinvention is shown in an exposed view. The oximetry sensor of thepresent invention comprises a foam wrap member 12 including a fastener14, back film mounting member 16, LED assembly 18 and photodiode 20connected to a cable 22, support rings 24 for the LED assembly 18 andphotodiode 20, window film 26 for the LED assembly 18 and photodiode 20,and a top liner 28.

The foam wrap member 12 comprises a fabric and foam lamination having afastener attached thereto. The foam portion 30 of the foam wrap member12 comprises any suitable type foam, such as a polyester foam. Thefabric portion 32 of foam wrap member 12 comprises any suitable fabric,such as a fabric having a plurality of loops integrally formed therein,which may be readily engaged by a plurality of fastening members locatedon the fastener 14 of the foam wrap member 12. The fastener 14 attachedto the foam wrap member 12 comprises a molded plastic member having aplurality of hooks 15 formed on one surface thereof to engage theplurality of loops formed in the fabric portion 32 of the foam wrapmember 12. The combination of the fastener 14 having a plurality ofhooks 15 formed on one surface thereof and the fabric portion 32 of thefoam wrap member 12 is commonly referred to as a VELCRO type fastenercomprised of synthetic materials which adhere when pressed together. Thefoam portion 30 and fabric portion 32 of the foam wrap member 12 aresecured together by any suitable means of fastening, such as adhesivebonding. The fastener 14 of the foam wrap member 12 is secured to thefoam portion 30 and fabric portion 32 of the foam wrap member 12 by anysuitable means, such as adhesive bonding, sewing, ultrasonic staking,the natural tendencies of these materials to adhere to each other, etc.

The back film mounting member 16 comprises any suitable plastic filmmember, such as polyethylene film, having any suitable adhesive coatingon each side thereon to adhesively retain the back film mounting member16 to the foam portion 30 of the foam wrap member 12 and adhesivelyattach the LED assembly 18 and photodiode 20 thereto. While the backfilm mounting member 16 serves to adhesively attach the LED assembly 18and photodiode 20 to the foam wrap member 12, the back film mountingmember may be deleted and the assembly 18 and photodiode 20 adhesivelyretained on the foam wrap member 12 by other means, such as by the topliner 28.

The LED assembly 18 includes a red light emitting diode and an infraredlight emitting diode adjacently mounted forming a rectangular shapedmember. As is known in oximetry, the transmission of light in the redrange of the spectrum, i.e., at a wave length of approximately 660nanometers through blood is substantially affected by the amount ofoxygenated hemoglobin present in the blood. The transmission of light inthe infra-red range of the spectrum, i.e., at a wave length ofapproximately 940 nanometers through blood is substantially unaffectedby the amount of oxygenated hemoglobin present in the blood. Oximetersuse this principle to alternately illuminate the blood through thetissue with light of the foregoing respective wave lengths.

The photodiode 20 is sensitive to red light and infrared light. Thephotodiode 20 alternately senses radiated red and infrared energy.

The cable 22 is connected to the LED assembly 18 and photodiode 20 viasuitable wire connections thereto. The cable 22 includes a suitableconnector 40 (not shown) on the end thereof for connecting the LEDassembly 18 and photodiode 20 to a suitable display. Alternatively, theLED assembly 18 and photodiode 20 may be connected to a suitable devicethrough the use of a flexible printed circuit or the like.

The support rings 24 are formed of any plastic material suitable for usewith the LED assembly 18 and photodiode 20, such as a soft pliant rubberlike material. The support rings 24 are installed around the LEDassembly 18 and photodiode 20 to provide comfort to the patient duringuse of the pulse oximetry sensor. Alternately, if the foam wrap member12 is of sufficient thickness for comfort to the patient or a thin LEDassembly 18 and photodiode 20 are used, the support rings 24 may beeliminated.

The window film 26 is used to cover the support rings 24 surrounding theLED assembly 18 and photodiode 20. The window film 26 should betransparent to red and infra-red light and allow the transmissionthereof therethrough readily. The window film 26 may be of such materialas polyethylene or the like. The window film 26 is adhesively coated onone side thereof to retain the support rings 24, LED assembly 18, andphotodiode 20 and be secured to the back film mounting member 16.

The top liner 28 comprises a highly comfortable and breathablepolyurethane material having two polyethylene windows 29 therein for thetransmission of red and infra-red light therethrough. If desired, thetop liner 28 may be coated with a suitable adhesive coating on one sidethereof to adhesively bond to the window film 26 and to the back filmmounting member 16. However, it is not necessary that the top liner 28be coated with adhesive on one side thereof as the back film mountingmember 16 is coated with adhesive to adhesively bond the LED assembly18, photodiode 20, support rings 24, window film 26, and the top liner28 thereto.

Referring to drawing FIG. 2, the oximetry sensor 10 of the presentinvention is shown in relation to the finger 7 of a patient before theinstallation thereon. As shown, the oximetry sensor 10 comprises agenerally elongated rectangular shaped foam wrap member 12 which isinitially disposed generally perpendicularly to the finger 7 of apatient before the installation thereon. The LED assembly 18 andphotodiode 20 are generally arranged to be located on opposite sides ofthe patient's finger 7 when the pulse oximetry sensor is installedthereon. The pulse oximetry sensor 10 of the present invention may beused on other sites of a patient, such as the heel, etc., depending uponthe desired point of application.

Referring to drawing FIG. 3, the oximetry sensor 10 is shown installedon the finger 7 of a patient. As installed, the oximetry sensor 10 iswrapped around the finger 7 of a patient so that the LED assembly 18 islocated generally opposite the photodiode 20 in engagement with the skinand/or the fingernail of the finger 7. In this manner, the red andinfra-red light emitted from the LED assembly 18 is transmitted throughthe tissue of the finger 7 and detected by the photodiode 20. The foamwrap member 12 of the oximetry sensor 10 is generally wound around thefinger 7 so that the fastener 14 having hooks 15 thereon of the member12 releasably engages the loops 33 of the fabric portion 32 of themember 12. To adjust the oximetry sensor 10 on the finger 7 of a patientsince the foam wrap member 12 is compressible and conformable, themember 12 may be rotated around the finger 7 without unfastening or thefastener 14 being disengaged or removed from engaging the fabric portion32 of the foam wrap member 12 and the member 12 unwrapped from engagingthe finger 7. Since the foam wrap member 12 is compressible andconformable, the amount of force caused by the wrapping of the oximetrysensor 10 around the finger 7 may be adjusted and controlled to providethe desired amount of force during use without causing discomfort ortrauma to the finger 7 of a patient. Additionally, since the fastener 14may be engaged with the fabric portion 32 of the foam wrap member 12 forrepeated installation, adjustment, and removal of the sensor 10 from thefinger 7 of a patient, the oximetry sensor 10 can be repeatedly reusedon the same patient without any substantial loss of fastening ability.

Referring to drawing FIG. 4, the first step in the manufacture of theoximetry sensor 10 is illustrated. The top liner 28 is formed having thewindow film 26 adhesively bonded thereto with the window film 26 havingan adhesive coating on the bottom side also; i.e., the window film 26 isadhesively coated on one side. Next, the support rings 24 are placed onthe bottom of the window film 26 being retained thereon by the adhesiveon the bottom of the window film 26. As previously stated, the use ofthe support rings 24 is optional depending upon the amount of cushioningprovided by the foam wrap member 12 for the comfort of the patient.

Referring to drawing FIG. 5, the cable 22 is provided with a suitableconnector 40 on one end thereof while the LED assembly 18 and thephotodiode are installed on the appropriate wires of the cable 22 on theother end thereto. The LED assembly 18 and the photodiode 20 are placedwithin the support rings 24 being retained therein by the adhesivecoating on the bottom of the window film 26 while a portion of the cable22 also engages a portion of the adhesive coating on the window film 26.

Referring to drawing FIG. 6, the foam wrap member 12 has back filmmounting member 16 installed thereon by the member 16 adhesivelyengaging the foam portion 30 of the member 12 as the back film mountingmember 16 is formed having an adhesive coating on each side thereof.

Referring to drawing FIG. 7, the completed subassembly 36 is shown ofthe cable 22 having connector 40 on one end thereof and LED assembly 18and photodiode 20 on the other end thereof while a portion of the cable22, support rings 24, LED assembly 18, and photodiode 20 are retained bythe adhesive coating on the bottom of window film 26 which, in turn, isretained by the adhesive coating on the top of the window film 26 to topliner 28. The completed subassembly 38 is shown of the foam wrap member12 having back film mounting member 16 adhesively retained thereon. Thesubassembly 36 is joined to the subassembly 38 by the adhesive coatingon the top of back film mounting member 16 engaging the adhesive coatingon the bottom of the window film 26. In this manner, the subassembly 36is securely mounted on the subassembly 38 in the desired positionthereon.

Referring to drawing FIG. 8, the oximetry sensor 10 of the presentinvention is shown in its assembled, completed form ready for use on apatient.

From the foregoing it is easily seen that the oximetry sensor 10 of thepresent invention offers any advantages over the prior art sensors. Theoximetry sensor 10 is generally easily manufactured from inexpensivematerials, is easy to use on a patient, is easy to repeatedly reuse on apatient, and is comfortable in use on a patient. Since the oximetrysensor 10 of the present invention does not use adhesive to attach thesensor 10 to a patient, the sensor 10 is quickly applied to a patientand has no adhesive contacting the skin of a patient to causediscomfort. The oximetry sensor 10 of the present invention is easilyadjustable and has an extended life in comparison to adhesively retainedsensors. The oximetry sensor 10 also is easy to reposition on a patientfor optimum signal and comfort. Additionally, since the foam wrap memberis conformable and compressive, the oximetry sensor may be easilyrepositioned on a patient without unwrapping the sensor from thepatient. The combination of the foam wrap and fabric back providescomfort to the patient and a readily conformable sensor. The foam wrap,fabric back, and polyurethane liner also allows the sensor to breath andhelp minimize sweating of a patient. As such, the oximetry sensor 10 ofthe present invention is very suitable for use on patients with bumswith minimum trauma to the bums. Since the oximetry sensor 10 of thepresent invention is not retained on the patient through the use ofadhesives, the sensor is very suited to patients who may be sensitive orhave allergies to adhesives. As previously stated, the sensor 10 isnon-traumatic during use since it is conformable and compressible. Sincethe oximetry sensor 10 is simple to manufacture from relativelyinexpensive materials, it is disposable but has a long life during useas compared to adhesive type sensors as well as being readily reusableon a patient. The oximetry sensor 10 of the present invention may bereadily trimmed to customize the application of the sensor to a patient.Additionally, the oximetry sensor 10 may be sterilized, if so desired,since the materials from which the sensor is made will acceptsterilization.

It can be seen from the foregoing that changes, deletions andmodifications to the oximetry sensor of the present invention may bemade which fall within the scope of the invention. Additionally, it canbe further seen from the foregoing that changes, additions, deletionsand modifications to the method of manufacturing the oximetry sensor ofthe present invention may be made which fall within the scope of theinvention.

We claim:
 1. An oximetry sensor comprising:an elongated foam wrap memberincluding a fastener on one end thereof, the foam wrap member having afoam member having a first side, a second side, and a thickness, thefoam member having a fabric member attached thereto on the first side ofthe foam member; an LED assembly and a photodiode located on the secondside of the foam member; a window film attached to the other end of thesecond side of the foam member of the foam wrap member for covering theLED assembly and photodiode; and a top liner attached to a portion ofthe window film and covering a portion of the window film.
 2. Theoximetry sensor of claim 1, further comprising:a back film mountingmember.
 3. The oximetry sensor of claim 1, further comprising:supportrings for the LED assembly and the photodiode.
 4. The oximetry sensor ofclaim 1, further comprising:a cable connected to the LED assembly andthe photodiode.
 5. The oximetry sensor of claim 2, wherein the back filmmounting member isadhesively secured to a portion of the foam wrapmember.
 6. The oximetry sensor of claim 5, wherein the fastener of thefoam wrap member includes a plurality of hooks thereon to engage thefabric member of the foam wrap member.
 7. The oximetry sensor of claim6, wherein the fabric member of the foam wrap member includes aplurality of loops therein to engage the plurality of hooks located onthe fastener.
 8. The oximetry sensor of claim 3, wherein the supportrings are adhesively secured to a portion of the window film.
 9. Theoximetry sensor of claim 1, wherein the support rings are adhesivelysecured to a portion of the back film mounting member and the windowfilm.
 10. The oximetry sensor of claim 1, wherein the top liner isadhesively secured to a portion of the window film.
 11. The oximetrysensor of claim 1, wherein the LED assembly and the photodiode areconnected to a cable having a connector on one end thereof.
 12. Theoximetry sensor of claim 11, wherein the cable includes a connector onone end thereof.
 13. The oximetry sensor of claim 1, wherein the supportrings are adhesively secured to a portion of the back film mountingmember and a portion of the window film.
 14. An oximetry sensorcomprising:an elongated foam wrap member including a fastener securedthereto having a plurality of hooks thereon, the foam wrap member havinga foam portion secured to a fabric portion, the fastener attached to oneend of the elongated foam wrap member; a back film mounting memberattached to a portion of the foam wrap member adjacent the other endthereof, the back film mounting member attached to a side of the foamportion of the foam wrap member opposite the fabric portion of the foamwrap member; an LED assembly and a photodiode, the LED assembly and thephotodiode attached to a portion of the back film mounting member; awindow film covering the LED assembly and the photodiode, the windowfilm secured to a portion of the back film mounting member; and a topliner attached to a portion of the back film mounting member, the windowfilm covered by the top liner.
 15. The oximetry sensor of claim 14,wherein the back film mounting member is adhesively secured to a portionof the foam wrap member.
 16. The oximetry sensor of claim 14, whereinthe fastener of the foam wrap member includes a plurality of hooksthereon to engage the fabric portion of the foam wrap member.
 17. Theoximetry sensor of claim 16, wherein the fabric portion of the foam wrapmember includes a plurality of loops therein to engage the plurality ofhooks located on the fastener.
 18. The oximetry sensor of claim 14,wherein support rings are adhesively secured to a portion of the windowfilm.
 19. The oximetry sensor of claim 14, wherein support rings areadhesively secured to a portion of the back film mounting member and thewindow film.
 20. The oximetry sensor of claim 14, wherein the top lineris adhesively secured to a portion of the window film.
 21. The oximetrysensor of claim 14, wherein the window film is transparent to red andinfrared light.
 22. An oximetry sensor comprising:an elongated foam wrapmember including a fastener having a plurality of hooks thereon, thefoam wrap member having a foam portion having a first side and a secondside, and having fabric members attached to the first side and thesecond side of the foam portion, and having the fastener attached to oneend of the elongated foam wrap member; an LED assembly and a photodiodelocated on the elongated foam wrap member; and a top liner secured to aportion of the foam wrap member adjacent the other end thereof, the topliner securing the LED assembly and the photodiode in position on thefoam wrap member.
 23. An oximetry sensor comprising:an elongated foamwrap member including a fastener having a plurality of hooks thereon,the foam wrap member having a foam portion enclosed by a fabric member,the fastener attached to one end of the elongated foam wrap member; anLED assembly and a photodiode located on the elongated foam wrap member;and a top liner secured to a portion of the foam wrap member adjacentthe other end thereof, the top liner securing the LED assembly and thephotodiode in position on the foam wrap member.